PROCEEDINGS OF SOCIETIES. 299 
the parallel pair of slender stipes for a single broad band-like 
one. If he has really done so, the distinctions then would be 
reduced mainly to de Brebisson’s plant being attached (by the 
stipes) to Conferve, whilst de Bary’s is free; the central point 
of the colony having been formerly occupied by the primary or 
original cell. It seems strange that de Bary does not allude at 
all in his paper to the resemblance of Cosmocladium to Nigeli’s 
genus Dictyospherium. Mr. Archer would refer to it, however, 
not as indicating a real affinity, for de Bary had no doubt proved 
Cosmocladium to belong to Desmidiex, while there could be little 
doubt Dictyospherium did not. But there is still sufficient 
resemblance to justify a simultaneous allusion to them. In 
Dictyospherium (of which three species are known) the cells 
(differently figured according to the species) are supported on 
dichotomously branched slender stipes, originally starting from 
a common centre. Simultaneously with the division of the peri- 
pheral cells of the group, a new branching of the stipes takes 
place, so that each ultimate branch is surmounted by a cell. In 
D. Ehrenbergianum the stipes are exceedingly slender and deli- 
cate, more pronounced and coarser in D. reniforme (Bulnheim), 
and most so in a species Mr. Archer had brought forward, 
D. constrictum (ejus), and described in Minutes of October 19th, 
1865. But, apart from the Desmidian character of the cells 
themselves in Cosmocladium, the genus Dictyospherium is dis- 
tinguished by the stipes being single and filiform, not double 
and expanded intermediately, and the cells both intermediate and 
terminal. Still, apart as these two genera must be placed, their 
outward resemblance to one another justifies this brief allusion 
to them. The cells in both grow in families or colonies (Stécke, 
de Bary), in both they are supported on stipes, the stipes in both 
exceedingly slender, delicate and colourless, seemingly in both a 
more dense filiform development of similar gelatine to that which 
encompasses the aggregate family ; and moreover in one species, 
Dictyospherium constrictum, Arch., the cells are notably con- 
stricted. Hence there is some probability that they might be 
confounded by observers, or referred to one and the same genus. 
But apart from the differences of stipes and habit of growth 
above alluded to, see de Bary’s paper (1. c.) for indubitable proof 
of the position of Cosmocladium in the Family Desmidiee—both 
forms, if distinct, representing a Cosmarium mounted on astipes 
whilst the new growths in Dictyospherium is by simple division 
into like daughter-cells, and the genus must seemingly take its 
place in Palmellacez, near Mischococcus (Nag.). 
Dr. Richardson exhibited the various stops he had contrived to be 
fitted under the stage of the microscope for viewing the markings 
on diatoms, but as there was no stand present to which he could 
adjust them, he was obliged to defer showing them in use. 
Mr. Archer showed the circulation of the cell-contents in 
Nitella, a trite but always a highly curious spectacle. 
